There has been a murder in a reunion party. Chris Lawrence was found in the closet, stabbed in the back (how ironic). You have deduced that the only suspects are those at the party: Sam from Stanford, Yvonne from Yale, Harry from Harvard, Carrie from Cornell, Bart from Brown, Diana from Dartmouth, and Peter from UPenn (Chris was from Columbia). Problem is, the only lead you have is a piece of paper that Chris wrote:












2 + 1 + 19 + 5 - 64

Who is the killer?

Hint 1:

When you interview all of the suspects, you find that one thing they all say is along of the lines of, "Chris was always the first of his class, and received letters after letters of congratulation."

  • 2
    $\begingroup$ Who is Randall? $\endgroup$
    – Sid
    Feb 10, 2018 at 20:29
  • $\begingroup$ Oh oops, I changed Randall to Chris and forgot to change the last one, editing that $\endgroup$
    – Terry Yu
    Feb 10, 2018 at 20:46
  • 2
    $\begingroup$ Why di you say that being stabbed in the back is ironic? $\endgroup$ Feb 10, 2018 at 21:06
  • $\begingroup$ Wait, just double checking, UPenn is University of Pennsylvania, right? $\endgroup$ Feb 10, 2018 at 21:53
  • 1
    $\begingroup$ @Sid I am! :-P $\endgroup$ Feb 12, 2018 at 0:57

3 Answers 3


The piece of paper points toward ...

... Sam.

Mark Dickinson has found out that ...

... the first letters of the piece of paper are base-64 for the code to a pastebin document that contains a number sequence. (The OP has pointed out an error in the sequence and has corrected the link.)

Now, ...

... the number sequence is strictly monotonic. It counts up from 0 to 151 in steps of either one or two. The length of the sequence is 104, which is divisible by 8.

Taking only the least significant bit of each number, we can get thirteen eight-digit binary numbers. The sequence starts with:

    0, 1, 3, 4, 6, 7, 9, 10, ...

Taking only the least significant bit – 0 for even numbers, 1 for odd numbers –, we get:

    0110 0110

all of the 8-digit numbers start with 0, which and yield numbers in the range of printable ASCII characters. Two of the numbers in the middle are 0010 0000 or 32, which is the space character in ASCII. Converting to ASCII yields:

    fear the tree

Using this information ...

... and given that the only useful information we have is which university everyone was from, this points towards Sam from Stanford, which has a tree in its seal.

(But Dartmouth College also has trees in its seal, but they don't take centre stage as in Stanford's. The seals of the other universities all have books of some kind, or dead trees. And this is going by the university allegiance only. we don't know if the suspects are Sam Sequoia, Yvonne Yew, Harry Hawthorn, Carrie Cedar, Bart Birchwood, Diana Datepalm, and Peter Pine, for example.)

  • $\begingroup$ You got it! "Fear the tree" points to Stanford because it is a popular motto there, seen on their merchandise. $\endgroup$
    – Terry Yu
    Feb 15, 2018 at 2:51
  • $\begingroup$ @Terry I knew it was him because (rot13) Fgnasbeq vf gur bayl aba-Vil Yrnthr $\endgroup$
    – ferret
    Feb 15, 2018 at 5:10
  • $\begingroup$ Didn't know about the Sranford merchandise, but that actually lessens the already weak importance of the paper. It's as if someone with Nike sneakers were arrested because the victim wrote "Just Do It" in their diary. (Btw, Chris must have known about the murder beforehand. How else would he have time to come up with a two-step cipher and even post the relevant data to pastebin? Well, either that, or the death was very slow.) $\endgroup$
    – M Oehm
    Feb 15, 2018 at 6:13

Another partial answer, building on the one from North and the following comments from M Oehm:

Applying base64 decoding to the string "bmFmNHVHemQ" consisting of the first letters (following the hint) of each line of text gives "naf4uGzd". That appears to give a pastebin URL that looks relevant.

The paste contains a list of 103 numbers, on 7 lines (it's not clear to me whether the line breaks are significant). The numbers are nonnegative integers, and are in increasing order; the increase is always either one or two. The sequence starts: [0, 1, 3, 4, 6, 7, 9, 10, 12, 13, 15, 16, 18, 19, 20, ...]. Taking differences and subtracting one gives a binary sequence of length 102 that starts [0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, ...]. I'm not sure where to go from there, or even if this is useful. edit from OP: I've gotten the number sequence wrong (sorry about that!) The real sequence is here.

  • $\begingroup$ This is close but not quite the correct number sequence oeis.org/A032766 $\endgroup$ Feb 12, 2018 at 6:11
  • $\begingroup$ Wait how would it be base 64 when it says -64? $\endgroup$ Feb 12, 2018 at 18:21

Partial answer:

I dont know if this is a coincidence, but if the numbers represant letters in an a=1, b=2, etc. then 2+1+19+5 spells "base". I feel as though thats a keyword, but U cant pinpoint exactly which cipher.

  • 1
    $\begingroup$ I think that the last line could spell base64. (But the first letters of each word don't decode to anything useful, not even after extending the names with the correct first names.) $\endgroup$
    – M Oehm
    Feb 11, 2018 at 18:29
  • $\begingroup$ It's suspicious that the result of doing base64 decode on the first letters of each word gives just letters and digits, though, rather than random-looking bytes. $\endgroup$ Feb 11, 2018 at 18:36
  • $\begingroup$ But it's too long for an imgur link. And the tinyurl link doesn't exist. $\endgroup$
    – M Oehm
    Feb 11, 2018 at 18:44
  • $\begingroup$ You're definitely on the right track. $\endgroup$
    – Terry Yu
    Feb 11, 2018 at 19:03

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